(a) Field of the Invention
The present invention relates to a method and device for encoding and decoding stereoscopic video. More specifically, the present invention relates to a method and device for encoding and decoding stereoscopic video into an encoding stream by using a conventional MPEG-4 MAC (multiple auxiliary component.)
(b) Description of the Related Art
A MVP (multi-view profile) method for extending two-dimensional video encoding techniques in the MPEG-2 technology has been developed as a conventional stereoscopic video encoding method. As to the MVP method, an encoding structure of a base layer for performing encoding by using motion compensation corresponds to that of the MPEG-2 MP (main profile), and hence, one of the right and left images is reconstructed when the conventional 2-dimensional video decoder reconstructs the data of the base layer, thereby maintaining compatibility with the existing 2-dimensional video decoder system. An encoder of an enhancement layer uses correlation information provided between the right and left images to perform encoding. This is a method for performing encoding by using temporal scalability, and the MPEG-4 standard has also defined the temporal scalability using stereoscopic video encoding.
The above-noted prior art has been disclosed by U.S. Pat. No. 5,612,735 entitled “Digital 3D/stereoscopic video compensation technique utilizing two disparity estimates.” Regarding the '735 patent on the temporal scalability basis, a base layer uses a motion compensation algorithm and DCT (discrete cosine transform) base algorithm to encode images of the left eye, and an enhancement layer uses disparity information of between the base layer and the enhancement layer to encode the images of the right eye without motion compensation for the images of the right eye.
Also, as to the U.S. Pat. No. 5,619,256 entitled “Digital 3D/stereoscopic video compensation technique utilizing disparity and motion compensated predictions,” the base layer uses a motion compensation algorithm and DCT base algorithm to encode images of the left eye, and the enhancement layer uses information on the motion compensation between the images of the right eye and disparity of between the base layer and the enhancement layer to encode the images of the right eye on the temporal scalability basis in the like manner of the '735 patent. This method achieves efficient compression rates by performing encoding by using motion and disparity information, but the method has a complicated encoding structure and it is difficult to realize the method in the hardwired manner, and the method requires a large amount of calculation when processing HDTV images.
Therefore, in the case of encoding stereoscopic video by using temporal scalability, an additional multiplexer for transmitting respective encoding streams output by the base layer and the enhancement layer as a single stream is problematically needed in order to simplify a synchronization problem between the right and left images.
Conventional multi-view video encoding methods include a method for performing encoding by using a disparity map having disparity vector values of pixels, which has been disclosed by U.S. Pat. No. 6,055,274 entitled “Method and apparatus for compressing multi-view video.”
The '274 patent encodes the total image data of the first image (a left image), and generates a disparity map having disparity vector values for respective pixels from the first image and a second image (a right image) to perform encoding on the motion compensated disparity vectors, and uses a reconstructed first image after the encoding to disparity-compensate for a reconstructed disparity map and encode residual image data of between the generated second image and the input second original image. This method problematically outputs a plurality of encoding streams, and additionally requires a multiplexer for transmitting them in a single stream format.
In order to use the conventional MPEG codecs for 2-dimensional images, and perform simple synchronization between the right and left images in the stereoscopic video, a method for reducing the respective right and left images by ½ and converting them into 2-dimensional standard images has been proposed in five methods in the transactions of “3D video standards conversion, stereoscopic displays and applications,” by Andrew Woods, Tom Docherty, and Rolf Koch (VII, California, February 1996, Proceedings of the SPIE vol. 1653A).
The above technique is also published in U.S. Pat. No. 5,633,682 entitled “Stereoscopic coding system.”
The invention published as '682 selects odd-field images for the images of the left eye and even-field images for the images of the right eye to convert them into a single image, and accordingly performs MPEG encoding on the converted single image with respect to the existing 2-dimensional images. This method considers a shuttering method for alternately displaying the right and left images in the case of displaying the stereoscopic video, and the method is not suitable for polarized displays that concurrently display the right and left images.